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Noise under braking

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MrClean

MrClean

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Location
Kansas City
RC Driving Style
  1. Bashing
I got my LST back together and was breaking in the engine. When it would get a little speed and I let off the throttle, it was like the brakes were applied. It wouldn't do it all the time, other times it would coast just fine. With the TX and RX turned on, but engine not running, I could push the truck and it would roll fine. I think I may have had something in the slipper clutch in a bind. So I took it apart and checked everything, put it back together and it seems to be ok now.
One thing I noticed while checking out the clutch, when I would roll the truck and then apply the brakes, there would be a click in the front end, almost like the diff was slipping. There doesn't seem to be any binding and I pulled the diffs apart when I broke it down and didn't see any obvious signs of wear. Since I'm not real familiar with LST, I didn't know if the noise was normal.
 
Well clicking noise is never normal. I was going to suggest to check your clutch when you were talking about the slowing issuea but it seema like you got that all fixed now.
 
i can't remember if the LST comes with dog bones or CVD's but i'd say check the drive cups or bones. its possible you have a tiny pebble thats catching and causing the click and slowing you down.
 
My LST is doing the same thing in the front end. In addition do the clicking noise the front end turns about 1/3 the speed of the rears. I am on the road for the next three weeks but when I get home I am going to crack the front diff. My LHS suggested tossing the grease and adding diff oil. This is no big deal as the LST diffs have o-rings. Anyway, they think the grease is keeping the gears and pins from wearing but allowing the diff to slip.

Please let me know what you find?

savagefan04 said:
i can't remember if the LST comes with dog bones or CVD's but i'd say check the drive cups or bones. its possible you have a tiny pebble thats catching and causing the click and slowing you down.
Click to expand...

LST's have dog bones. That is a good idea though--can't hurt to check the cups while you are at it!
 
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I think I figured out the clicking, it was actually in the transmission. I put an FOC in when I had the rig taken apart for cleaning. Apparently I didn't push the drive cups tight against the transmission on both sides. When I applied the brake, there was enough slop to allow the drive-shaft to push towards the back and the output drive gear was slipping on the spider gear in the transmission. I didn't see any stripped teeth on either gear so I put it back together and made sure the drive cups were tight. I'll find out for sure next time I run it, hopefully tomorrow.

Another thing I noticed is with the brakes. Is it all or nothing with the LST? There are 2 metal discs and 3 metal bars, are there no pads? It seems like as soon as the brakes engage they lock up the wheels.
 
My LST is doing the same thing in the front end. In addition do the clicking noise the front end turns about 1/3 the speed of the rears. I am on the road for the next three weeks but when I get home I am going to crack the front diff. My LHS suggested tossing the grease and adding diff oil. This is no big deal as the LST diffs have o-rings. Anyway, they think the grease is keeping the gears and pins from wearing but allowing the diff to slip.

Please let me know what you find?


Quote:
Originally Posted by savagefan04
i can't remember if the LST comes with dog bones or CVD's but i'd say check the drive cups or bones. its possible you have a tiny pebble thats catching and causing the click and slowing you down.

LST's have dog bones. That is a good idea though--can't hurt to check the cups while you are at it!
Click to expand...

The Lst/2's have CVD's the lst2 has 8MM and the lst i belive are 6mm not sure there i dont think that your problem is with the diffs or it could be but mostlikely is the grub screw that holds the CVD to the diff pinnion check those and threadlock them (ill post a pic if you dont know wich ones) Those come loose and cause major slipping

Anyway, they think the grease is keeping the gears and pins from wearing but allowing the diff to slip.
Click to expand...

i suggest diff oils too I'm currently running 10k front and 7k rear i also upgraded to the HD diff cups since the stock cups wear out fast with diff oils

oh, maybe its slipping because you snaped a pin inside the diff the ones that go inside of the bevel gears that outputs to the cup check those too they snap if it did buy a titanium drill bit and cup a piece off it (about the same size of the pin) and replace it with that :D

arc

Another thing I noticed is with the brakes. Is it all or nothing with the LST? There are 2 metal discs and 3 metal bars, are there no pads? It seems like as soon as the brakes engage they lock up the wheels.
Click to expand...


i would suggest that you upgrade to these
http://www.losi.com/Products/Features.aspx?ProdId=LOSB3606
they are the high performance brake pads they replace the 3 metal bars and give you a better feel when brakin also the LST2 linkage is a great upgrade to the LST and its this one it also gives you a better feel
http://www.losi.com/Products/Features.aspx?ProdId=LOSB4204
 
After I posted this thread I found those pads on ebay, I'll definitely be upgrading to those. They're pretty inexpensive and hopefully will provide the better brake performance I'm looking for. I haven't looked at the LST2 brake linkage yet, so I'll be sure to check that out too. Thanks for the links.
 
I had a braking issue on my aftershock not too long after I got it. The metal pads would float and bind themselves when I wasn't braking. Made for a nasty rattling sound.

I replaced them with a 3MM CF disk and high torque (170oz) servo. The brakes are much more smooth, but not nearly as aggressive. No more binding though.

I made a vid of the binding:

I put a drill on one of the wheel axles to spin the drivetrain like I was coasting. It would literally lock the wheels. Then I'd spin the drill backwards a few revolutions and the disks would straighten out.
 
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Arcboyz said:
i suggest diff oils too I'm currently running 10k front and 7k rear i also upgraded to the HD diff cups since the stock cups wear out fast with diff oils

oh, maybe its slipping because you snaped a pin inside the diff the ones that go inside of the bevel gears that outputs to the cup check those too they snap if it did buy a titanium drill bit and cup a piece off it (about the same size of the pin) and replace it with that.
Click to expand...

Thanks for the suggestions! I will check into it when I get back home.
 
Thanks for the post Olds, that is a pretty crazy issue. I'll keep that in mind, looks like it really locked the drive line up pretty hard.
Mine was doing more along the lines of a light braking, haven't run it much since then, hopefully tomorrow I'll have a chance to put a couple tanks through the new motor.
 
That's how mine started, like the brakes were dragging a bit at slow speeds. Then 10-15 tanks later, it got to what you see in the vid and would do it at a decent roll and lock up the wheels. Not fun!

Keep your eye out for it. Having it do what mine did isn't good for diffs and cvd's.
 
olds97_lss said:
That's how mine started, like the brakes were dragging a bit at slow speeds. Then 10-15 tanks later, it got to what you see in the vid and would do it at a decent roll and lock up the wheels. Not fun!

Keep your eye out for it. Having it do what mine did isn't good for diffs and cvd's.
Click to expand...

I was thinking about getting the fiberglass pads, do you think that might help to keep them from locking up? I might just do that for now until I can afford a new servo and the brake set up you're using.
 
It helps, but you still get wear pretty quick which causes binding.

Maybe try the integy CF disks. My buddy ran those with the stock servo and it would still almost lock up. He was using them with the fiber pads from the LST2 though. Even though, running two disks sandwiched between 3 steel pads will give you less aggressive brakes, but shouldn't bind and lock up like steel on steel. Also shouldn't need a killer servo like my single disk setup. I'm contemplating pickup up those integy's and giving them a try. If I do, I'll let you know how it goes.
 
I noticed a build up of something on the discs, I wonder if that's also causing the brakes to grab so hard. I guess I should have cleaned them off when I had everything apart. I'm a genius sometimes. :loser:
 
Well I got a chance to continue the break-in of the new motor today. I noticed that the 'binding' issue is back. One thing I noticed this time that I didn't find in the past, the CB is getting smoking hot. I'd expect them to get hot, but I can barely touch it. I think it may be time for a new clutch shoes. I want to go to aluminum and these are the original shoes anyway. I think I'll order them and check into getting the brakes changed over to a single composite pad.
 
MrClean said:
Well I got a chance to continue the break-in of the new motor today. I noticed that the 'binding' issue is back. One thing I noticed this time that I didn't find in the past, the CB is getting smoking hot. I'd expect them to get hot, but I can barely touch it. I think it may be time for a new clutch shoes. I want to go to aluminum and these are the original shoes anyway. I think I'll order them and check into getting the brakes changed over to a single composite pad.
Click to expand...

Let us know what you go with and how they work? I am sure I will be needing to replace mine sooner or later...
 
I'm afraid I will run out of decent weather before I get the parts upgraded. We've had a pretty mild fall so far, hopefully it'll hold out awhile. I really need to get an electric to satisfy the addiction during this winter.
 
Bah! That's madness!!!! Waterproof it up and bash it in the winter. I find that it's best to use an old tired engine I don't care about for winter bashing due to temps, but man, it is still fun bashing in the snow!
 
The LST motor is brand new so that's out as a winter motor. The 3.3 in my Revo has almost 3 gallons on it so I'm considering running it this winter and possibly getting a new motor next spring for it.
 

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